fix: 增加判断

coupon/details.html

@@ -351,9 +351,11 @@
             let detailsConfig = JSON.parse(localStorage.getItem('product_detail'));
             goodsCount = localStorage.getItem('goodsCount');
             this.backAble = goodsCount > 1;//多个商品才有返回
+            if (detailsConfig) {
                 this.bgcolor = detailsConfig.button_color;
                 this.ftColor = detailsConfig.font_color;
                 this.describe = detailsConfig.describe;
+            }
 
             //商品详情
             goodsDetail = JSON.parse(localStorage.getItem('goodsInfo'));